Novel Unipolar Shilla Technique for Complex EOS Provides Lasting Correction and Controlled Growth.

Background: The Shilla technique offers direct apical control and allows continuous cranial and caudal guided growth in early-onset scoliosis (EOS), eliminating the need for repeated surgeries. For cases where bipolar growth is not feasible, we developed a modified "unipolar" Shilla technique, allowing for asymmetric growth modulation with fusion at the opposite end. This study examines the feasibility and effectiveness of this approach in a complex EOS population.

Methods: We conducted a retrospective review of all Shilla cases performed by 3 surgeons over 11 years at a single institution. We identified patients treated with the unipolar Shilla technique and collected socio-clinical variables, radiographic parameters, and growth metrics. "Rod slide" was measured to determine intra-Shilla construct growth.

Results: Thirteen patients treated with unipolar Shilla were identified. The mean major coronal curve decreased from 69 degrees preoperatively to 19 degrees postoperatively. Thoracic height (T1 to T12) increased from 17.5 to 21.9 cm, and T1 to S1 height from 26.8 to 34.0 cm. Rod slide in those with complete follow-up averaged 9.6 mm, and all patients had more than 5 mm of Shilla growth. Overall, there was one unplanned return to OR due to discomfort from a prominent rod, which was trimmed.

Conclusions: The unipolar Shilla technique provided excellent correction of severe spinal deformities with minimal complications. Although growth was modest in most cases, this technique is potentially beneficial for patients requiring definitive apical control with limited growth potential or those who may have difficulty with follow-up.

Level of evidence: Level IV-retrospective case series.